Objective The purpose of this study was to investigate whether a simple, biologically robust method for inducing calcification of degenerate intervertebral discs (IVD) could be developed to provide an alternative treatment for patients requiring spinal fusion. Design Nucleus pulposus (NP) cells isolated from 14 human IVDs were cultured in monolayer and exposed to osteogenic medium, 1,25-dihydroxyvitamin D3 (VitD3), parathyroid hormone (PTH), and bone morphogenic proteins (BMPs) 2/7 to determine if they could become osteogenic. Similarly explant cultures of IVDs from 11 patients were cultured in osteogenic media with and without prior exposure to VitD3 and BMP-2. Osteogenic differentiation was assessed by alkaline phosphatase activity and areas of calcification identified by alizarin red or von Kossa staining. Expression of osteogenic genes during monolayer culture was determined using polymerase chain reaction and explant tissues assessed for BMP inhibitors. Human bone marrow-derived mesenchymal stromal cells (MSCs) were used for comparison. Results Standard osteogenic media was optimum for promoting mineralization by human NP cells in monolayer. Some osteogenic differentiation was observed with 10 nM VitD3, but none following application of PTH or BMPs. Regions of calcification were detected in 2 of the eleven IVD tissue explants, one cultured in osteogenic media and one with the addition of VitD3 and BMP-2. Conclusions Human NP cells can become osteogenic in monolayer and calcification of the extracellular matrix can also occur, although not consistently. Inhibitory factors within either the cells or the extracellular matrix may hinder osteogenesis, indicating that a robust biological fusion at this time requires further optimization.

中文翻译：

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人类髓核细胞的成骨分化是否可能成为生物性脊柱融合术？

目的这项研究的目的是研究是否可以开发出一种简单的，生物学上可靠的诱导变性椎间盘钙化（IVD）的方法，为需要脊柱融合术的患者提供替代治疗。从14个人类IVD中分离出的设计髓核（NP）细胞进行单层培养，然后暴露于成骨培养基，1,2-25-二羟基维生素D3（VitD3），甲状旁腺激素（PTH）和骨形态发生蛋白（BMP）2/7，以确定如果他们可以成骨。同样，在有或没有事先暴露于VitD3和BMP-2的成骨培养基中培养来自11位患者的IVD的外植体培养物。成骨分化通过碱性磷酸酶活性评估，钙化区域通过茜素红或von Kossa染色鉴定。使用聚合酶链反应确定单层培养过程中成骨基因的表达，并评估BMP抑制剂的外植体组织。使用人骨髓来源的间充质基质细胞（MSC）进行比较。结果标准成骨培养基最适合促进单层人NP细胞矿化。用10 nM VitD3观察到一些成骨分化，但施用PTH或BMP后未见到。在11个IVD组织外植体中的2个中检测到钙化区域，其中1个在成骨培养基中培养，1个在添加VitD3和BMP-2的条件下培养。结论人NP细胞可以单层成骨，细胞外基质也可以钙化，尽管不一致。细胞或细胞外基质中的抑制因子可能会阻碍成骨，